CK Li, HL Yuen, SY Ha, CK Li, CW Lee, NK Leung

Acute lymphoblastic leukaemia (ALL) is the commonest childhood malignancy. The Hong Kong Paediatric Haematology & Oncology Study Group has started a new ALL treatment protocol since January 1993. The treatment was stratified according to: white cell count (WCC), age, immunophenotyping and cytogenetic abnormalities. The new protocol used non-radiation prophylaxis to central nervous system (CNS) for standard risk and intermediate risk patients, by regular intrathecal methotrexate (Reg A) or high dose methotrexate with regular intrathecal methotrexate (Reg B). High risk patients were treated with cranial irradiation 18 Gy (Reg C). The preliminary result of this protocol was analysed at 1 April 1996. In 1993-1994, 58 cases of childhood ALL were diagnosed. Infants less than 1 year and children older than 15 years were excluded. The male to female ratio was 1:1. The median age was 6.1 years (range 1.2 - 14.9). The median presenting WCC was 21. 1x10⁹/L (range 1-652). 93% cases were B lineage (common: 70%, early pre-B/pre-B :23%), and 7% cases were T cells. Cytogenetic studies were performed successfully in 37 cases, 5 had Philadelphia chromosome, 5 with t(1 ;19), hyperdiploidy was found in 5. 8 patients received bone marrow transplant (BMT), 3 in second remission and 5 in first remission. 46 patients (79%) were treated with non-radiation regimen: 29 Reg A and 17 Reg B. With a median follow up of 28 months (range 15 - 39), 8 patients had relapsed: 4 BM (2 Reg A, 1 Reg B, 1 Reg C), 3 CNS (2 Reg A, 1 Reg C), 1 BM + CNS (Regimen A). 6 patients died: 3 from relapsed leukaemia, 3 from complications of treatment. Excluding patients receiving BMT at first remission, 83% of patients were surviving in continuous remission. The preliminary results showed that this new protocol had no increase in CNS relapse despite non-radiation prophylaxis in majority of patients.